This invention relates to a cylinder head for an engine and more particularly to an improved cylinder head porting arrangement and associated manifold system for an internal combustion engine.
As is well know, engines normally have a cylinder block in which the cylinder bores are formed and a cylinder head which is detachable connected to the cylinder block and which has surfaces or recesses that cooperate with the cylinder bores to form the combustion chambers of the engine. With overhead valve engines, the intake and exhaust passages are formed in the cylinder head and extend from the combustion chamber surface in the sealing face of the cylinder head to external openings in the cylinder head to which intake and/or exhaust manifolds are connected. The cylinder head also has a valve chamber which is closed by a valve cover that is affixed to the cylinder head and which is removable for servicing the valve mechanism and the camshafts, if overhead camshafts are employed. Hence, there are a number of surfaces on the exterior of the cylinder head which must be machined so as to improve sealing.
Frequently, particularly with automotive applications, the intake passages terminate on one side of the cylinder head and the exhaust passages terminate on the other side of the cylinder head. The lower surface must be machined to provide the sealing surface for the cylinder block and the upper surface of the cylinder head must be machined to form the sealing surface for the valve cover. In addition, the surfaces around the intake and exhaust passages where they exit the cylinder head also must be machined so as to permit good sealing with the intake and exhaust manifold. Obviously, this requires complicated machining operations.
It is therefore, a principal object of this invention to provide an improved cylinder head arrangement for an internal combustion engine.
It is a further object of this invention to provide an improved cylinder head arrangement for an internal combustion engine wherein the surfaces of the intake and exhaust passages which must be machined lie in the same plane as the lower and upper sealing surfaces of the cylinder so as to facilitate and simplify machining operations.
With the induction system for an internal combustion engine, it is well known that the length of the induction system can be tuned to certain running conditions so as to provide optimum charging efficiency. Frequently this requires a long intake passage. However, when the engine is employed for powering a vehicle, such as an automobile, the spaced available in the engine compartment may not permit the use of long intake passages.
It is, therefore, a still further object of this invention to provide an improved compact induction system for an engine that permits the attainment of long lengths in relatively small volumetric areas.
In connection with the induction system for an engine, it is desirable to maintain a relatively straight unencumbered flow path to achieve high performance and good volumetric efficiencies at wide-open throttle conditions. However, it is also desirable to induce turbulence in the combustion chamber, particularly at low speed and low load conditions. There have been proposed types of flow control valves in the intake passage of the cylinder head which can be utilized to permit low restriction under high speed, high load operation, and also the attainment of turbulence under low speed, low load conditions.
However, in order to be able to achieve this result, it is necessary that the control valve be positioned relatively close to the intake port. This presents certain problems, and can significantly complicate the configuration of the cylinder head, if the flow control valve is positioned directly in the cylinder head.
It is, therefore, a still further object of this invention to provide a compact cylinder head assembly wherein a flow control valve can be positioned in the assembly but apart from the cylinder head, per se.